This project will provide the most comprehensive study to date on the genetics of male sexual orientation. The main justifications for basic research on the etiology and development of sexual orientation include that it carries much social importance and interest, and that such research will illuminate sexual characteristics of brain, mind and behavior, thus informing society about currently unknown biological aspects behind male sexual orientation. Male sexual orientation is known to be heritable, but is multifactorial in nature with multiple genetic and environmental factors contributing to its etiology. Genetic linkage studies have found strong evidence of specific genetic loci (pericentromeric chromosome 8 and chromosome Xq28). Genome-wide association studies (GWAS) for sexual orientation are only just beginning to surface. There is a great need to combine studies to elucidate the genetics of this important biological trait. In this proposal, we plan to conduct meta-analysis of several genome-wide linkage studies (GWLS) and GWAS to maximize the ability to identify genetic targets for future study. Our specific aims are as follows 1. Determine the most promising linkage regions by meta-analyzing GWLS for male sexual orientation: our own GWLS of 409 ASPs, plus other collaborative GWLS of 155 ASPs, totaling 564 ASPs (representing 91% of the field's ASPs). 2. Conduct a meta-analysis of available GWAS for male sexual orientation using our European ancestry (EA) GWAS of 701 homosexual and 1,214 heterosexual men, plus other collaborative GWAS, en masse currently totaling 5,752 homosexual and 39,286 heterosexual men, and growing. Our results will be instrumental to a better understanding of the genetic contributions to male sexual orientation and also enable future approaches aimed at locating genetic variants contributing to trait variation, especially re sequencing. Finding linkage, association, or eventually contributory genetic variants will open a gateway to additional research that will inform the study of genetic and environmental mechanisms and developmental events influencing sexual orientation.